<!DOCTYPE html>
<html>
	<head>
		<meta charset="utf-8">
		<title></title>
	</head>
	<body>
    <script>
      let arr = [1,2,3,4]
      arr = arr.map((item)=>{
        return item * 2
      })
      let arr2 = arr.map(item => item * 2)
      console.log(arr)
      console.log(arr2)
    </script>
	</body>
</html>
